"I will see you one day in top form. While Xiaobo was sick, he also looked at life and death with some distance, so I also have to readjust. I will be with you again when my situation generally improves," she said.

The name of the film-maker, the place and date of filming, were not specified, but it would be unusual for the video to be released without the knowledge of the authorities. Plainclothes security agents guard Liu Xia's Beijing apartment.

"It is certain that she was forced by the authorities to make this video," Hu Jia, a Chinese dissident and friend of the couple, told AFP on Saturday.

"How can anyone who does not even enjoy freedom express her will freely?"

He died aged 61 while still in custody at a Chinese hospital on July 13, after losing his battle with liver cancer.

His death triggered rage and frustration among the dissident community and an outpouring of grief in semi-autonomous Hong Kong, where pro-democracy forces also contend with an increasingly assertive Beijing.